The semiconductor material is widely applied in the photoelectronic devices like light-emitting diode, laser diode and photovoltaic cell, and how to reduce the production cost and simplify the processes to increase the manufacturing efficiency has become a main topic for the industry.
FIG. 1A to FIG. 1G show a generally-known process flow of forming a photoelectronic device. As FIG. 1A shows, a substrate 10 is provided first, which is conductive. As FIG. 1B shows, a semiconductor stack layer 12 is formed on the substrate 10, and the semiconductor stack layer 12 includes at least a first conductive type semiconductor layer 120, an active layer 122, and a second conductive type semiconductor layer 124 from up to down. As FIG. 1C shows, a metal layer 14 is formed on the semiconductor stack layer 12 by the evaporation technology. Next, as FIG. 1D shows, a photoresist 16 is formed on the metal layer 14. As FIG. 1 E shows, a portion of the photoresist 16 is reacted with the light passing through the mask 18 and leaves another portion of the photoresist 16′ on the metal layer 14. As FIG. 1F shows, a portion of the metal layer 14 not covered by the photoresist is etched to form a first electrode 20. Finally, as FIG. 1G shows, the photoresist 16 is removed, and a second electrode 22 is formed under the substrate 10 by the evaporation, then a photoelectronic device 100 is formed.
From the above description, it is known that the size and the position of the electrode of the photoelectronic device is defined by the size and the position of the opening 180 of the mask 18. Only one kind of metal material can be used to form the metal layer by the above-mentioned process, and the selection of the metal material is also restricted by the evaporation technology. Furthermore, more processes like the exposure, lithography, etching, and removal of the photoresist are needed to form a electrode, which increases the production cost of manufacturing the photoelectronic device.